Search

Background: Surgical approaches to the cavernous sinus (CS) and middle cranial fossa (MCF) can be challenging, particularly for young neurosurgeons. The anteromedial (Mullan's) triangle is a triangle by the side of the CS and constitutes part of the floor of the MCF. The contents include the sphenoid sinus, superior ophthalmic vein, and sixth cranial nerve. The literature contains very little research that has precisely defined and measured the anteromedial triangle while considering anatomical variances minimally., Methodology: The present study was conducted on the skulls of 25 adult human cadavers which were dissected to expose the anteromedial (Mullan's) triangle on both sides. After precisely defining the triangle on each side, measurements of the three borders were taken, and using Heron's formula, the area of each triangle was calculated., Results: On average, the length of the medial border was 12.5 (+ 3.1 mm); the length of the lateral border was 9.9 (+ 3.1 mm); the length of the base was 10.75 (+ 2.4 mm) and the area of the anteromedial triangle was 43.9 (+ 15.06 mm 2 )., Conclusion: Precise anatomical knowledge of the Mullan's triangle enables the treatment of disorders in often deformed anatomy or difficult-to-access structures. That is the reason it is important to gain a thorough understanding of the surgical anatomy and to adopt a safe procedure., (© 2024. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Aim: The main aim of this study was to evaluate 6-month closure success in surgery for isolated or non-isolated temporal bone osteomeningeal breach (OMB). Secondary objectives were to analyze complications of closure and correlations between success and breach, treatment and patient data., Material and Method: This was a single-center retrospective observational study of patients who underwent surgery for temporal bone OMB via a middle cranial fossa or transmastoid approach in a French university teaching hospital between 2007 and 2022, with follow-up of at least 6months. Patients with superior semicircular canal dehiscence were excluded. Study data comprised gender, age, body mass index, OMB etiology, mode of discovery, audiometric and radiological data, surgical technique, length of hospital stay and postoperative complications. The primary endpoint was absence of a cerebrospinal fluid leak on MRI at 6months. Fisher's exact test or Chi 2 test were used for qualitative data and Student t-test for quantitative data., Results: The closure success rate was 87%: 81% (3 recurrences) in the middle cranial fossa group of 16 patients and 93% in the transmastoid group of 14 patients. Postoperative audiometry showed significant improvement (P=0.0016) for air conduction in the middle cranial fossa group. Five patients (17%) operated on via the middle cranial fossa approach and 1 (7%) operated on via the transmastoid approach had postoperative complications. OMB was in the tegmen mastoideum in 8 patients (29%), tegmen tympani in 7 (25%), tegmen antri in 4 (14%), tegmina antri and tympani in 3 (11%), antri and mastoideum in 1 (8%) and in the whole tegmen in 5 (18%). Eleven OMBs were lateral to the superior semicircular canal, 13 medial and 4 on either side., Conclusion: The transmastoid approach is indicated in case of associated middle-ear procedures, patients aged over 75years or OMB lateral to the superior semicircular canal. The middle cranial fossa approach is reserved for OMB located medial to the superior semicircular canal patients under 75years of age without associated ossicular procedures. For patients with OMB medial to the superior semicircular canal who require middle-ear surgery, a combined approach can be used., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

The contributions of Laurent Princeteau (1858-1932) to anatomy and to the establishment of neurosurgery have largely gone unrecognized, perhaps because he was educated and practiced in a French city other than Paris at a time when Paris was one of the chief centers of medicine in Europe. After completing a thesis describing an iliac artery anomaly and obtaining the distinguished agrégé teaching degree, Princeteau began his surgical career at the University of Bordeaux. Within 10 years, he became chef de clinique and one of the busiest surgeons in Saint-André Hospital, as well as head of the anatomy institute and professor of anatomy at the dental school. In 1891, he achieved the rank of surgeon. In the field of general anatomy, he was recognized for novel cadaveric preparations and vascular perfusion techniques. In the neurosciences, he made important contributions to the anatomy of the trigeminal nerve and trigeminal neuralgia. In 1898, Princeteau supervised a thesis that addressed contemporary surgical approaches to the trigeminal complex. In the course of this effort, he identified a bony prominence near the petrous apex (the retrogasserian tubercle) that helped to locate the gasserian ganglion. The surgical significance of the retrogasserian tubercle was quickly acknowledged in the European neurosurgical community and was noted in French textbooks of anatomy. Thierry de Martel, a founding member of the French neurosurgical School, named the tubercle after Princeteau. To the rest of the world, however, it remained almost unknown., (Copyright © 2024. Published by Elsevier Inc.)

Objective: Compare outcomes for subjects who underwent middle cranial fossa (MCF) or transmastoid (TM) repair of superior semicircular canal dehiscence (SSCD)., Study Design: Retrospective cohort study., Setting: Quaternary-care, academic neurotology practice., Methods: Subjects who underwent MCF or TM repair of SSCD between December 1999 and April 2023 were identified. Main outcome measures included demographic data, length of surgery and hospital stay, clinical presentation, and audiometric testing., Results: Ninety-three subjects (97 ears) who underwent surgery for SSCD met inclusion criteria: 58.8% (57) via MCF, 39.2% (38) via TM, and 2.0% (2) via TM + MCF. Median operative time was shorter for the TM (35) compared to the MCF (29) approach (118 vs 151 minutes, P < .001). Additionally, median hospital stays were shorter for TM (36) compared to the MCF (56) approach (15.3 vs 67.7 hours, P < .001). Overall, 92% (49/53) of MCF and 92% (33/36) of TM surgeries resulted in an improvement or resolution of one or more symptoms (P = .84). There was no significant preoperative to postoperative change in the median air conduction pure-tone average (PTA), air-bone gap, or word recognition score in both the MCF and TM groups (P > .05). Improvements of >10 dB in the pre- to postoperative absolute change in bone conduction PTA were noted in 3 subjects in the MCF group and 4 subjects in the TM group (P = .49)., Conclusion: The TM approach for SSCD demonstrates shorter operative times and length of hospital stay. The TM and MCF approaches have comparable audiometric and clinical outcomes., (© 2024 American Academy of Otolaryngology–Head and Neck Surgery Foundation.)

Objective: To evaluate the efficacy of a nonabsorbable, synthetic graft for the reconstruction of spontaneous middle fossa (sMF) cerebrospinal fluid (CSF) leaks., Patients: Six adult patients (age ≥16 yr) who had sMF CSF leaks surgically repaired within an 18-month period at a single university hospital using synthetic, nonbiological, nonabsorbable graft (Neuro-Patch) and a retrospective control group of five patients undergoing multilayer MF repair with autologous grafts., Interventions: MF repair through a combined transmastoid/MF approach using Neuro-Patch or multilayer autologous grafts., Main Outcome Measures: The incidence of postoperative leak within 6 months postoperatively was the main outcome measure; we also recorded the need for lumbar drain, additional hearing loss, length of inpatient stay, body mass index, previous meningitis, preoperative increased intracranial pressure, and age., Results: In the Neuro-Patch group, there was no postoperative CSF leak without the need for lumbar drain. We observed no additional hearing loss; patients were monitored for 2 days without any readmissions. Increased intracranial pressure (four of six), previous episodes of meningitis (two of six) or obesity (five of six) did not affect patient outcomes. Demographic and prognostic factors were the same for the control group. However, one patient needed lumbar drain postoperatively because of residual leak; lumbar drain was used in one more case (two of five cases), whereas three of five patients had to stay for longer than 2 days (5 d)., Conclusions: Our pilot study suggests the use of Neuro-Patch via combined transmastoid/MF approach as an effective technique with minimum, if any morbidity; it could be of particular benefit for patients with larger MF dura defects. A larger number of patients are required to strengthen the evidence., Competing Interests: The authors disclose no conflicts of interest., (Copyright © 2024, Otology & Neurotology, Inc.)

Here, we report a very rare case of spontaneous intraventricular tension pneumocephalus. This case concerns a 40-year-old patient with medical history of a tumor of the pineal region and a secondary hydrocephalus treated by multiple ventriculoperitoneal shunts. He presented in the emergency room because of unusual headaches, nausea, and visual loss. In addition, he reported slight rhinorrhea in the past few weeks. The initial brain computed tomography scan revealed a spontaneous intraventricular tension pneumocephalus. There was no history of recent head trauma and no sign of disconnection of the shunt system. A complementary radiologic assessment including a thin-slice bone computed tomography scan and a radioisotope cisternography revealed an osseous defect and an isotope leakage at the junction between the tegmen tympani and the squamous part of the left temporal bone. A middle cranial fossa surgery was performed to repair the osteo-meningeal breach., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: The dysmorphogenetic arachnoid cysts' pathomechanism is most favoured, and about 50% occur as middle cranial fossa cysts (MCFAC). Still being rare, management options are yet evolving. We described the clinico-radiological features, management and early outcomes of participants with MCFAC in our service., Methods: This prospective cohort study involved 29 pediatric participants recruited (from electronic health records, using ICD G93.0 D016080 for arachnoid cysts) between 01/01/2023 and 31/06/2023, following informed consent according to the ethical approval. All participants had neuro-imaging confirmed MCFAC. Baseline and follow-up data were retrieved and analyzed using summary (mean, standard deviation) and inferential (ANOVA, t-test) statistics., Results: They were averagely aged 6.2 ± 4.48 years and were mostly males (89.7%). 24.1% were asymptomatic. The commonest symptoms (n = 38) were headaches (23.7%), developmental delays (15.8%), eye complaints (15.8%) and cephalomegaly (7.9%). They were predominantly left-sided (89.7%). Galassi (G) 3 lesions were less (24.1%), with G2 and G1 lesions evenly sharing the rest. The average cyst volume was 58.4 ± 80.83cm 3 ; there were significant differences (F = 4.682; p = 0.018) between the average volumes for G1 (14.4 ± 22.42cm 3 ), G2 (61.7 ± 89.92cm 3 ) and G3 (122.5 ± 94.37cm 3 ) lesions. 44.8% of the participants had rigid-endoscopic cysto-cisternotomy (all between the ICA and oculomotor nerve into the interpeduncular cistern, using ventriculostomy forceps); including all G3, 50% of G2 and no G1 (had serial clinico-radiological observation) lesion. The average pre- (117.42cm 3 ) and post-operative (53.48cm 3 ) cyst volumes showed significant (t = - 2.797, p = 0.021) reductions., Conclusion: Middle cranial fossa arachnoid cysts occur predominantly amongst males, in middle childhood and left-sided. The treatment-related patient series are largely symptomatic, unlike the largely asymptomatic, screening-related series. Higher Galassi grade lesions presented with progressively, significantly larger cyst volumes and higher likelihoods of surgery. The average post-operative cyst volume at follow-up averagely showed almost 60% reduction from the pre-operative. All participants reported clinical remission., Competing Interests: Declarations. Ethics approval: The protocol for this study as part of a Candidate of Medical Science - Neurosurgery (analogous to Doctor of Philosophy) thesis proposal was reviewed by the Local Ethical Committee (LEC) of the I. M. Sechenov First Moscow State Medical University, Moscow. Upon approval, it was granted 2023 protocol number 04. This ensured that the research was in accordance with the 1964 Helsinki Declaration and its subsequent amendments for ethical human studies. All participants assented, while their parents granted written informed consent to participate in this study, after reading the information leaflet for this study. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: Arachnoid cysts are commonly encountered benign cystic structures and often come to attention as incidental findings following cranial imaging. Surgical intervention rates vary in different studies; however, rupture of cyst and subdural collection with mass effect are some of the indications for surgical intervention. In this study, we aimed to evaluate our operated cohort of middle fossa arachnoid cysts to determine the rate of traumatic subdural collection in this cohort and further assess outcomes., Methods: A retrospective review of all consecutive operated middle cranial fossa arachnoid cysts was carried out for the period 2010 to 2024. Demographics including age, sex, Galassi type, surgical technique for fenestration, preceding history of trauma, presence of papilloedema, and complications following surgery were extracted. Indication for surgery included papilloedema and headaches or increasing head circumference or rupture and subdural collections. Arachnoid cysts managed with CSF diversion as primary surgery were excluded., Results: Over the study period, 21 fenestrations of the arachnoid cysts were carried out in 19 patients with mean age of 7 years and M:F ratio of 2.2:1 (laterality: 9 right-sided and 10 left-sided). These included seven Galassi 2 and twelve Galassi 3 arachnoid cysts. At presentation, 10 had papilloedema, 5 with no papilloedema, and 4 with no available ophthalmological assessment. Fenestration of cyst included 12 microscopic, 6 endoscopic, and 3 combined approaches. Of the operated cohort, 8 were due to rupture of arachnoid cyst and subdural collections causing mass effect. Of 8 cases of ruptured arachnoid cyst with subdural collections, 75% had clear history of preceding head injury in the context of accidental or sports-related injuries. Two patients required redo-fenestration (10.5%), 1 patient required temporary lumbar drain (5.2%), and 2 patients required cysto-peritoneal shunts (10.5%)., Conclusion: Rupture of arachnoid cysts and subdural collections although rare can be associated with head injury in majority of cases. All operated cases belonged to grade 2 and 3 Galassi., Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: Arachnoid cysts are primarily dysembryogenetic splitting or duplication of the embryonic meningeal mesenchyme, hence the paediatric preponderance. Neuroendoscopic cysto-cisternostomy is now the favoured treatment option. We pooled data on middle fossa arachnoid cysts (MCFAC) demographics, clinical presentations, cyst characteristics, neuro-endoscopic cysto-cisternostomy and its outcomes., Evidence Acquisition: Using search words (from the keywords; 'endoscopic treatment' and 'middle fossa arachnoid cysts') combined using Boolean operators, a systematic review of the PubMed and Cochrane CENTRAL was started on 1 st February 2023, as per protocol (PROSPERO CRD42023394345); 65 records and then 46 reports were screened, 169 cases were pooled from the 19 recruited reports for the qualitative and quantitative syntheses, after methodological assessment (significantly excellent 57.9% quality) using the Joanna Briggs Institute critical appraisal tools., Evidence Synthesis: The male-to-female ratio was 2.4:1, with a weighted average-age of 11.25 years in the modal childhood (32.0%) age-group. Headaches (53/29.3%), seizures (30/16.6%) and macrocephaly (25/13.8%) were the commonest presentations. Right-sided (30/55.6%) and Galassi II (55/48.3%) and III (53/46.5%) lesions were common. Rigid (124/93.9%) endoscopes aided cysto-cisternostomy using mostly bipolar diathermy (31/43.7%) and ventriculostomy forceps (18/25.4%); creating one (22/18.3%), two (14/11.6%) or more (78/65.0%) stomas. Fenestration sites were specifically CNIII&ICA (32/25.8%), CNII&ICA (27/21.8%), CNIII&tentorium cerebelli (23/18.6%), CNIII&PCA (1/0.8%) and through the side of CNVI (1/0.8%) into the pre-pontine cistern. Good clinical and radiological outcomes were reported., Conclusions: Largely excellent-to-good quality, low-level evidence reported MCFACs presenting in childhood with headaches, seizures and macrocephaly. At least two fenestrations using bipolar-diathermy/forceps and balloon-catheter expansion were used for cysto-cisternostomy, with good outcomes.

The foramen spinosum, one of the important openings at the base of the cranium, is the opening through which the middle meningeal artery enters the cranium. The variations of the foramen spinosum should be well known to be an important landmark in middle fossa surgeries and to understand better the clinical conditions related to the middle meningeal artery passing through it. A total of 35 bones (32 cranial base and 3 separate sphenoid bones) of individuals of unknown age, sex, and ethnicity in the Laboratory of the Department of Anatomy, Gaziantep University, Faculty of Medicine were examined bilaterally in this study. One of the 35 bones was found to have a duplicated foramen spinosum on the left side and an absence foramen spinosum on the right side. Foramen spinosum variations should be considered in middle fossa approaches and procedures involving the middle meningeal artery., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 by Mutaz B. Habal, MD.)

Purpose: To assess the audiometric outcomes following surgical repair of spontaneous temporal bone cerebrospinal fluid otorrhea and compare different surgical approaches., Materials and Methods: Retrospective review of adults (≥18 years old) who underwent repair of spontaneous CSF leak between 2011 and 2022. Audiometric outcomes were compared across the three surgical groups: transmastoid, middle cranial fossa and combined., Results: Thirty-nine patients (40 ears) met the inclusion criteria (71.8 % females; mean age 59.77 +/- 12.4). Forty-two percent underwent transmastoid, 12.5 % middle cranial fossa and 45 % transmastoid-middle cranial fossa. Four patients (10 %) had recurrence, 3 in the transmastoid group and 1 in the combined approach. The mean change in air-bone gap (ABG) for all patients (postoperative-preoperative) was -7.4 (paired t-test, p-value = 0.0003). The postoperative ABG was closed in 28 (70 %) ears (postoperative ABG ≤ 15). The mean change in pure tone average (PTA) for all patients (postoperative-preoperative) was -4.1 (paired t-test, p-value = 0.13). The mean change in word recognition scores (WRS) for all patients (postoperative-preoperative) was -3 (paired t-test, p-value = 0.35). On multivariable analysis (controlling for site and reconstruction material), there was no significant difference in ABG, PTA and WRS change between surgical groups., Conclusions: Transmastoid, middle cranial fossa and combined approaches are all effective in treatment of spontaneous CSF leaks and all showed mean decrease in post-operative ABG. Transmastoid approach showed the greatest decrease in ABG and PTA (although middle cranial fossa approach shows the greatest decrease, when excluding profound hearing loss in a patient with superior canal dehiscence). Further studies comparing audiometric outcomes are needed., Competing Interests: Declaration of competing interest No conflicts of interest or funding were declared by any of the authors., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: To evaluate quality-of-life outcomes for patients with vestibular schwannomas (VS) undergoing a middle cranial fossa (MCF) approach., Study Design: Prospective study from 2018 to 2023., Setting: Tertiary academic institution., Patients: Adults with sporadic VS., Interventions: MCF., Main Outcome Measures: The primary outcome measure was the change in preoperative and 1-year postoperative Penn Acoustic Neuroma Quality-of-life (PANQOL) scores. Secondary outcome measures included hearing preservation and facial nerve function., Results: Of the 164 patients who underwent MCF for sporadic VS, 78 patients elected to voluntarily complete preoperative PANQOL assessments prior to surgery. Seventy-one (91%) of those 78 patients completed postoperative PANQOL surveys. Fifty (70%) of the respondents were female and the median age was 48 years (range, 27-71 years). Overall, at 1-year postsurgery, a minimal clinically important difference (MCID) was obtained in the hearing (mean difference, 10.5; 95% confidence interval [CI], 4.3-16.7) and anxiety (mean difference, 18.8; 95% CI, 11.7-25.9) domains. For patients with hearing preservation (n = 48, 68%), MCIDs were reached in the hearing (mean difference, 13.4; 95% CI, 6.3-20.6), anxiety (mean difference, 20.8; 95% CI, 11.8-29.9), energy (mean difference, 13.7; 95% CI, 3.6-23.8), pain (mean difference, 13.7; 95% CI, 3.6-23.8) domains, and overall PANQOL scores (mean difference, 12.7; 95% CI, 7.1-18.3). Postoperatively, 64 (90%) patients maintained a House-Brackmann I., Conclusions: To our knowledge, this is the largest study examining disease-specific QOL for VS patients undergoing MCF. Based on our institution's experience, MCF approach for small VS is associated with clinically meaningful improvements in QOL, hearing preservation, and excellent facial nerve outcomes., (Copyright © 2024, Otology & Neurotology, Inc.)

Purpose: This cadaveric anatomical study aimed to explore precise morphometric measurements of the eustachian tube (ET) and adjacent structures in the middle cranial fossa, focusing on identifying reliable surgical landmarks when traditional markers are compromised due to tumors or trauma., Methods: Twenty-two temporal bones from 11 adult cadavers (mean age: 75.70 ± 13.75 yr, range: 40-90 yr; sex: 5 females and 6 males) were dissected bilaterally. Surgical tools, including an operation microscope, endoscope, and digital caliper, were used for meticulous measurements. Parameters such as ET dimensions, distances between key points, and relevant angles were quantified, ensuring precise anatomical data., Results: ET width at the foramen spinosum (FS) level, the midline level, and the eustachian orifice level were measured as 2.18 ± 0.68, 2.42 ± 0.70, and 2.30 ± 0.74 mm, respectively. The distances from the zygomatic root (ZR) to FS, ET, superior semicircular canal (SSC), and internal carotid artery (ICA) were 29.61 ± 2.56, 23.28 ± 2.61, 26.53 ± 2.56, and 32.61 ± 3.69 mm, respectively. The angles between SSC-ZR-ICA and FS-ZR-ICA were measured as 36.57 ± 10.32 and 13.63 ± 3.72 degrees, respectively. No statistical difference was found between right-left or male-female measurements ( p > 0.05)., Conclusion: The present study offers invaluable insights for neurotological surgeons performing middle fossa approaches. ET and ZR may serve as crucial reference points, enhancing surgical orientation and minimizing risks during complex procedures. These precise anatomical data may empower surgeons, ensuring safer and more confident middle cranial fossa operations, even in challenging clinical scenarios., Competing Interests: The authors disclose no conflicts of interest., (Copyright © 2024, Otology & Neurotology, Inc.)

Background: Vestibular schwannomas (VS) are benign tumors arising from vestibular nerve's Schwann cells. Surgical resection via retrosigmoid (RS) or middle fossa (MF) is standard, but the optimal approach remains debated. This meta-analysis evaluated RS and MF approaches for VS management, emphasizing hearing preservation and Cranial nerve seven (CN VII) outcomes stratified by tumor size., Methods: Systematic searches across PubMed, Cochrane, Web of Science, and Embase identified relevant studies. Hearing and CN VII outcomes were gauged using the American Academy of Otolaryngology-Head and Neck Surgery, Gardner Robertson, and House-Brackmann scores., Results: Among 7228 patients, 56 % underwent RS and 44 % MF. For intracanalicular tumors, MF recorded 38 % hearing loss, compared to RS's 54 %. In small tumors (<1.5 cm), MF showed 41 % hearing loss, contrasting RS's lower 15 %. Medium-sized tumors (1.5 cm-2.9 cm) revealed 68 % hearing loss in MF and 55 % in RS. Large tumors (>3cm) were only reported in RS with a hearing loss rate of 62 %., Conclusion: Conclusively, while MF may be preferable for intracanalicular tumors, RS demonstrated superior hearing preservation for small to medium-sized tumors. This research underlines the significance of stratified outcomes by tumor size, guiding surgical decisions and enhancing patient outcomes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Objective: The goal of this study was to evaluate the feasibility of a minimally invasive approach to the middle cranial fossa using a novel endaural keyhole., Methods: The charts of all patients who underwent this novel minimally invasive approach to the middle cranial fossa were retrospectively reviewed. In addition, cadaveric dissection was performed to demonstrate the feasibility of the endaural keyhole to the middle cranial fossa., Results: Six patients (5 female and 1 male; age range 47-77 years) who underwent craniotomy for CSF leak (n = 3), intracerebral hematoma evacuation (n = 2), and tumor resection (n = 1) via the endaural subtemporal approach were identified. There were no approach-related complications noted. Representative imaging from cadaveric dissection is provided with a stepwise discussion of the procedure., Conclusions: The endaural subtemporal keyhole craniotomy provides a novel approach to middle fossa skull base pathology, as well as a minimally invasive approach to intra-axial pathology of the temporal lobe and basal ganglia. Further research is needed to establish the limitations and potential complications of this novel approach.

Background: In recent years, the endoscopic transorbital (TO) approach has gained increasing interest for the treatment of middle cranial fossa lesions. We propose a technical refinement to the conventional superior eyelid TO approach, which improves the surgical exposure and augments the working angles when targeting the opticocarotid region., Methods: Four embalmed adult cadaveric specimens (8 sides) were dissected at the Laboratory of Surgical Neuroanatomy of our institution. A TO approach was performed, with removal of the anterior clinoid process and the lateral orbital rim. Subsequently, the MacCarty keyhole was drilled in the superolateral orbital wall. Given that the lesser sphenoid wing was already drilled in the conventional TO craniectomy, the opening of the keyhole was essentially a lateral extension of the craniectomy., Results: The procedure was successfully conducted in all 4 orbits. Clinoidectomy was performed either before or after extending the craniectomy to the MacCarty point. Extending the craniectomy made anterior clinoidectomy easier, by increasing the surgical exposure, and allowing a more lateral entrance for the endoscope. The extension also facilitated frontal lobe retraction, and it facilitated the optic nerve and carotid artery manipulation. Postoperative computed tomography scans showed a minimal 10-mm craniectomy extension, which remained covered by the temporal muscle after reconstruction., Conclusions: The modified endoscopic TO approach with the extension of the craniectomy to MacCarty point improves surgical access and visualization of the opticocarotid region. This facilitates anterior clinoidectomy and optic nerve decompression. Although it implies judicious instrument manipulation and a larger incision size, further studies can define its potential benefits., (Copyright © 2024 Elsevier Inc. All rights reserved.)

There are several surgical approaches for vestibular schwannoma (VS) resection. However, management has gradually shifted from microsurgical resection, toward surveillance and radiosurgery. One of the arguments against microsurgery via the middle fossa approach (MFA) is the risk of temporal lobe retraction injury or sequelae. Here, we sought to evaluate the incidence of temporal lobe retraction injury or sequela from a MFA via a systematic review of the existing literature. This systematic review was conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. Relevant studies reporting temporal lobe injury or sequela during MFA for VS were identified. Data was aggregated and subsequently analyzed to evaluate the incidence of temporal lobe injury. 22 studies were included for statistical analysis, encompassing 1522 patients that underwent VS resection via MFA. The overall rate of temporal lobe sequelae from this approach was 0.7%. The rate of CSF leak was 5.9%. The rate of wound infection was 0.6%. Meningitis occurred in 1.6% of patients. With the MFA, 92% of patients had good facial outcomes, and 54.9% had hearing preservation. Our series and literature review support that temporal lobe retraction injury or sequelae is an infrequent complication from an MFA for intracanalicular VS resection., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: Although keyhole transorbital approaches are gaining traction, their indications have not been adequately studied comparatively. In this study the authors have defined them also as transwing approaches-meaning that they use the different facies of the sphenoid wing for cranial entry-and sought to compare the four major ones: 1) lateral orbitocraniotomy through a lateral canthal incision (LatOrb); 2) modified orbitozygomatic approach through a palpebral incision (ModOzPalp); 3) modified orbitozygomatic approach through an eyebrow incision (ModOzEyB); and 4) supraorbital craniotomy through an eyebrow incision (SupraOrb), coupled with its expanded version (SupraTransOrb)., Methods: Cadaveric dissections were performed at the neuroanatomy lab. To delineate the skull base exposure, four formalin-fixed heads were used, with two sides dedicated to each approach. The outer limits were assessed via image guidance and were mapped and illustrated accordingly. A fifth head was dissected purely endoscopically, just to facilitate an overview of the transwing concept. Qualitative features were also rigorously examined., Results: The LatOrb proves to be more versatile in the middle cranial fossa (MCF), whereas the anterior cranial fossa (ACF) exposure is limited to a small area above the sphenoid ridge. An anterior clinoidectomy is possible; however, the exposure of the roof of the optic canal is suboptimal. The ModOzPalp adequately exposes both the ACF and MCF. Its lateral trajectory allows the inferior to superior view, yet there is restricted access to the medial anterior skull base (olfactory groove). The ModOzEyB also provides extensive exposure of the ACF and MCF, but has a more superior to inferior trajectory compared to the ModOzPalp, making it more appropriate for pathology reaching the medial anterior skull base or even the contralateral side. The anterior clinoidectomy is performed with improved visualization of the optic canal. The SupraOrb provides mainly anterior cranial base exposure, with minimal middle fossa. An anterior clinoidectomy can be performed, but without any direct observation of the superior orbital fissure. Some MCF access can be accomplished if the lateral sphenoid wing is drilled inferiorly, leading to its highly versatile variant, the SupraTransOrb., Conclusions: All the aforementioned approaches use the sphenoid wing as skull base corridor from a specific orientation point; hence these are designated as transwing approaches. Their peculiarities mandate careful case selection for the effective and safe completion of the surgical goals.

Objective: Several pathologies either invade or arise within the orbit. These include meningiomas, schwannomas, and cavernous hemangiomas among others. Although several studies describing various approaches to the orbit are available, no study describes all cranio-orbital and orbitocranial approaches with clear, surgically oriented anatomical descriptions. As such, this study aimed to provide a comprehensive guide to the microsurgical and endoscopic approaches to and through the orbit., Methods: Six formalin-fixed, latex-injected cadaveric head specimens were dissected in the surgical anatomy laboratory at the authors' institution. In each specimen, the following approaches were modularly performed: endoscopic transorbital approaches (ETOAs), including a lateral transorbital approach and a superior eyelid crease approach; endoscopic endonasal approaches (EEAs), including those to the medial orbit and optic canal; and transcranial approaches, including a supraorbital approach, a fronto-orbital approach, and a 3-piece orbito-zygomatic approach. Each pertinent step was 3D photograph-documented with macroscopic and endoscopic techniques as previously described., Results: Endoscopic endonasal approaches to the orbit afforded excellent access to the medial orbit and medial optic canal. Regarding ETOAs, the lateral transorbital approach afforded excellent access to the floor of the middle fossa and, once the lateral orbital rim was removed, the cavernous sinus could be dissected and the petrous apex drilled. The superior eyelid approach provides excellent access to the anterior cranial fossa just superior to the orbit, as well as the dura of the lesser wing of the sphenoid. Craniotomy-based approaches provided excellent access to the anterior and middle cranial fossa and the cavernous sinus, except the supraorbital approach had limited access to the middle fossa., Conclusions: This study outlines the essential surgical steps for major cranio-orbital and orbitocranial approaches. Endoscopic endonasal approaches offer direct medial access, potentially providing bilateral exposure to optic canals. ETOAs serve as both orbital access and as a corridor to surrounding regions. Cranio-orbital approaches follow a lateral-to-medial, superior-to-inferior trajectory, progressively allowing removal of protective bony structures for proportional orbit access.

Objective: The lateral retrocanthal transorbital endoscopic approach (LRCTEA) facilitates trajectory to the middle fossa, preserving the lateral canthal tendon and thus avoiding postoperative complications such as eyelid malposition. Here, the authors sought to define the surgical anatomy and technique of LRCTEA using a stepwise approach in cadaveric heads and offer an in-depth examination of existing quantitative data from cadaveric studies., Methods: The authors performed LRCTEA to the middle cranial fossa under neuronavigation in 7 cadaveric head specimens that underwent high-resolution (1-mm) CT scans preceding the dissections., Results: The LRCTEA provided access to middle fossa regions including the cavernous sinus, Meckel's cave, and medial temporal lobe. The trajectories and endpoints of the approach were confirmed using electromagnetic neuronavigation. A stepwise approach was delineated and recorded., Conclusions: The authors' cadaveric study delineates the surgical anatomy and technique of the LRCTEA, providing a stepwise approach for its implementation. As these approaches continue to evolve, their development and refinement will play an important role in expanding the surgical options available to neurosurgeons, ultimately improving outcomes for patients with complex skull base pathologies. The LRCTEA presents a promising advancement in skull base surgery, particularly for accessing challenging middle fossa regions. However, surgeons must remain vigilant to potential complications, including transient diplopia, orbital hematoma, or damage to the optic apparatus.

Objective: The superior eyelid endoscopic transorbital approach (SETOA) provides a direct and short minimally invasive route to the anterior and middle skull base. Nevertheless, it uses a narrow corridor that limits its angles of attack. The aim of this study was to evaluate the feasibility and potential benefits of an "extended" conservative variant of the "standard" endoscopic transorbital approach-termed "open-door"-to enhance the exposure of lesions affecting the paramedian aspect of the anterior and middle cranial fossae., Methods: First, the authors described the technical nuances of the open-door extended transorbital approach (ODETA). Next, they documented its morphometric advantages over standard SETOA. Finally, they provided a clinical-anatomical application to demonstrate enhanced exposure and better angles of attack to treat lesions occupying the paramedian anterior and middle cranial fossae. Five adult cadaveric specimens (10 sides) initially underwent standard SETOA and then extended open-door SETOA (ODETA to the paramedian anterior and middle fossae). The adjunct of hinge-orbitotomy, through three surgical steps and straddling the frontozygomatic suture, converted conventional SETOA to its extended open-door variant. CT scans were performed before dissection and uploaded to the neuronavigation system for quantitative analysis. The angles of attack on the axial plane that addressed four key landmarks, namely the tip of the anterior clinoid process (ACP), foramen rotundum (FR), foramen ovale (FO), and trigeminal impression (TI), were calculated for both operative techniques and compared., Results: Hinge-orbitotomy of the extended open-door SETOA resulted in several surgical, functional, and esthetic advantages: it provided wider axial angles of attack for each of the target points, with a gain angle of 26.68° ± 1.31° for addressing the ACP (p < 0.001), 29.50° ± 2.46° for addressing the FR (p < 0.001), 19.86° ± 1.98° for addressing the FO (p < 0.001), and 17.44° ± 2.21° for addressing the lateral aspect of the TI (p < 0.001), while hiding the skin scar, avoiding temporalis muscle dissection, preserving flap vascularization, and decreasing the rate of bone infection and degree of orbital content retraction., Conclusions: The extended open-door technique may be specifically suited for selected patients affected by paramedian anterior and middle fossae lesions, with prevalent anteromedial extension toward the anterior clinoid, the foremost compartment of the cavernous sinus and FR and not completely controlled with the pure endoscopic transorbital approach.

Objective: To study the microanatomic structure of the subtemporal transtentorial approach to the lateral side of the brainstem, and to provide anatomical information that will assist clinicians to perform surgeries on the lateral, circumferential, and petroclival regions of the brainstem., Methods: Anatomical investigations were conducted on 8 cadaveric head specimens (16 sides) using the infratemporal transtentorial approach. The heads were tilted to one side, with the zygomatic arch at its highest point. Then, a horseshoe incision was made above the auricle. The incision extended from the midpoint of the zygomatic arch to one third of the mesolateral length of the transverse sinus, with the flap turned towards the temporal part. After removing the bone, the arachnoid and the soft meninges were carefully stripped under the microscope. The exposure range of the surgical approach was observed and the positional relationships of relevant nerves and blood vessels in the approach were clarified. Important structures were photographed and the relevant parameters were measured., Results: The upper edge of the zygomatic arch root could be used to accurately locate the base of the middle cranial fossa. The average distances of the star point to the apex of mastoid, the star point to the superior ridge of external auditory canal, the anterior angle of parietomastoid suture to the superior ridge of external auditory canal, and the anterior angle of parietomastoid suture to the star point of the 10 adult skull specimens were 47.23 mm, 45.27 mm, 26.16 mm, and 23.08 mm, respectively. The subtemporal approach could fully expose the area from as high as the posterior clinoid process to as low as the petrous ridge and the arcuate protuberance after cutting through the cerebellar tentorium. The approach makes it possible to handle lesions on the ventral or lateral sides of the middle clivus, the cistern ambiens, the midbrain, midbrain, and pons. In addition, the approach can significantly expand the exposure area of the upper part of the tentorium cerebelli through cheekbone excision and expand the exposure range of the lower part of the tentorium cerebelli through rock bone grinding technology. The total length of the trochlear nerve, distance of the trochlear nerve to the tentorial edge of cerebellum, length of its shape in the tentorial mezzanine, and its lower part of entering into the tentorium cerebelli to the petrosal ridge were (16.95±4.74) mm, (1.27±0.73) mm, (5.72±1.37) mm, and (4.51±0.39) mm, respectively. The cerebellar tentorium could be safely opened through the posterior clinoid process or arcuate protrusion for localization. The oculomotor nerve could serve as an anatomical landmark to locate the posterior cerebral artery and superior cerebellar artery., Conclusion: Through microanatomic investigation, the exposure range and intraoperative difficulties of the infratemporal transtentorial approach can be clarified, which facilitates clinicians to accurately and safely plan surgical methods and reduce surgical complications., Competing Interests: 利益冲突　所有作者均声明不存在利益冲突, (© 2024《四川大学学报（医学版）》编辑部 版权所有Copyright ©2024 Editorial Board of Journal of Sichuan University (Medical Sciences).)

Background and Objectives: The superior eyelid endoscopic transorbital approach has rapidly gained popularity among neurosurgeons for its advantages in the treatment, in a minimally invasive fashion, of a large variety of skull base pathologies. In this study, an anatomic description of the internal carotid artery (ICA) is provided to identify risky zones related to lesions that may be approached using this technique. In this framework, a practical roadmap can help the surgeon to avoid potentially life-threatening iatrogenic vascular injuries., Methods: Eight embalmed adult cadaveric specimens (16 sides) injected with a mixture of red latex and iodinate contrast underwent superior eyelid transorbital endoscopic approach, followed by interdural dissection of the cavernous sinus, extradural anterior clinoidectomy, and anterior petrosectomy, to expose the entire "transorbital" pathway of the ICA. Furthermore, the distance of each segment of the ICA explored by means of the superior eyelid endoscopic transorbital approach was quantitatively analyzed using a neuronavigation system., Results: We exposed 4 distinct ICA segments and named the anatomic window in which they are displayed in accordance with the cavernous sinus triangles distribution of the middle cranial fossa: (1) clinoidal (Dolenc), (2) infratrochlear (Parkinson), (3) anteromedial (Mullan), and (4) petrous (Kawase). Critical anatomy and key surgical landmarks were defined to further identify the main danger zones during the different steps of the approach., Conclusion: A detailed knowledge of the reliable surgical landmarks of the course of the ICA as seen through an endoscopic transorbital route and its relationship with the cranial nerves are essential to perform a safe and successful surgery., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Objective: To assess the rate of iatrogenic injury to the inner ear in vestibular schwannoma resections., Study Design: Retrospective case review., Setting: Multiple academic tertiary care hospitals., Patients: Patients who underwent retrosigmoid or middle cranial fossa approaches for vestibular schwannoma resection between 1993 and 2015., Intervention: Diagnostic with therapeutic implications., Main Outcome Measure: Drilling breach of the inner ear as confirmed by operative note or postoperative computed tomography (CT)., Results: 21.5% of patients undergoing either retrosigmoid or middle fossa approaches to the internal auditory canal were identified with a breach of the vestibulocochlear system. Because of the lack of postoperative CT imaging in this cohort, this is likely an underestimation of the true incidence of inner ear breaches. Of all postoperative CT scans reviewed, 51.8% had an inner ear breach. As there may be bias in patients undergoing postoperative CT, a middle figure based on sensitivity analyses estimates the incidence of inner ear breaches from lateral skull base surgery to be 34.7%., Conclusions: A high percentage of vestibular schwannoma surgeries via retrosigmoid and middle cranial fossa approaches result in drilling breaches of the inner ear. This study reinforces the value of preoperative image analysis for determining risk of inner ear breaches during vestibular schwannoma surgery and the importance of acquiring CT studies postoperatively to evaluate the integrity of the inner ear., Competing Interests: Conflicts of Interest and Source of Funding: This work was supported in part by the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health through Grant Numbers R01EB025964 and P41EB028741 (JJ). This work was also supported in part by the National Institutes of Health Institutional National Research Award, T32 5T32DC000040 (NB). Unrelated to this publication, Jagadeesan Jayender owns equity in Navigation Sciences, Inc. He is a coinventor of a navigation device to assist surgeons in tumor excision that is licensed to Navigation Sciences. Dr. Jagadeesan’s interests were reviewed and are managed by BWH and Partners HealthCare in accordance with their conflict of interest policies. This work was conducted with support from Harvard Catalyst. The Harvard Clinical and Translational Science Center (National Center for Advancing Translational Sciences, National Institutes of Health Award UL1 TR002541) and financial contributions from Harvard University and its affiliated academic health care centers. The content is solely the responsibility of the authors and does not necessarily represent the official views of Harvard Catalyst, Harvard University and its affiliated academic health care centers, or the National Institutes of Health., (Copyright © 2024, Otology & Neurotology, Inc.)

Calcium pyrophosphate dihydrate deposition disease (CPDD or pseudogout) is a degenerative joint disease. It is defined by the presence of calcium pyrophosphate dihydrate crystals. It usually manifests in the knee and wrist. Manifestation in the temporomandibular joint (TMJ) is only reported in case reports. We present a patient with CPDD mimicking a malignant tumor of the TMJ. A 53-year-old woman presented with progressive pain and a slow-growing swelling of the left TMJ. Imaging showed an extensive mass in the infratemporal fossa extending into the middle cranial fossa and compressing the temporal lobe. Assuming a potential malignancy, we excised the growth, which extended into the dura. We covered the resulting tissue defect within the primary surgery using a microsurgically anastomosed scapular flap and performed further reconstructive surgeries. Calcium pyrophosphate dihydrate crystals were found in the histopathologic examination of the excised tissue, resulting in the diagnosis of CPDD. That is a benign diagnosis, but we treated it like a malignancy. This leads us to the question, was there overtreatment? Tumoral CPDD in the TMJ can be a difficult diagnosis to obtain. The treatment remains controversial, but complete excision of the mass was performed in most reported cases., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Intradural exposure in the extended middle fossa anterior transpetrosal approach is traditionally limited to the inferior petrosal sinus inferomedially. Expanding bone removal of the petrous apex around the petrous internal carotid artery (ICA), underneath the trigeminal ganglion/mandibular nerve, and into the lateral component of the clivus can significantly expand the limits of this approach beyond the inferior petrosal sinus and allows for exposure of the midline structures, aspects of the contralateral inferior clival region, and, when high riding, the vertebrobasilar junction. To date, no descriptive techniques for drilling into the lateral clivus in this approach have been published. The authors provide a detailed stepwise description of their complete anterior petrosectomy, in use at their institution, that involves skeletonization of the posteromedial petrous ICA, gentle elevation of the trigeminal ganglion/mandibular nerve, removal of the infratrigeminal petrous apex, and two techniques for drilling into the lateral clivus along the petroclival fissure. These techniques provide a direct and unobstructed corridor to the midpetroclival region and ventral brainstem with greater maneuverability and enhanced control of the midline structures, which is especially useful for resection of petroclival meningiomas, chondrosarcomas, and giant vascular lesions of the mid- and upper basilar artery and its proximal branches.

Non-cavernous sinus (CS) dural arteriovenous fistulas (DAVFs) involving the sphenoid bone are rare entities that are easily confused with one another due to the complex structure and high variability of the venous system around the middle cranial fossa. We present a large retrospective study on middle cranial fossa non-CS DAVFs and review the literature on DAVF treatment in this location as well as relative anatomy. 15 patients had DAVFs involving the lesser sphenoid wing and 11 patients had DAVFs involving the greater sphenoid wing. Six patients presented with intracranial hemorrhage or subarachnoid hemorrhage (23.1%, 6/26). The most common symptoms were eye symptoms (38.5%, 10/26). Nineteen patients were treated with trans-arterial embolization (TAE) using liquid embolic agents and two patients were treated with transvenous embolization (TVE) using Onyx or in combination with coils. Surgical disconnection of the drainage veins was performed in five patients, with three cases experiencing unsuccessful TAE. Anatomic cure was achieved in 92.3% of the patients (24/26). Twelve patients had DSA and clinical follow-up from 3 to 27 months. There was one recurrence (8.3%) of the fistula in the patient two months after the initial complete occlusion. The majority of patients can be cured endovascularly. Laterocavernous sinus DAVFs may not be embolized by transvenous approach via the cavernous sinus because there is often no connection between them in most patients. A small percentage of patients may require surgical ligation to be cured., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Arachnoid cysts are usually asymptomatic, benign lesions commonly occurring in the middle cranial fossa. However, the cysts may rupture in rare cases causing intracystic or subdural hemorrhages with significant mass effect. We report two cases of middle cranial fossa arachnoid cyst with subdural hemorrhage with very different clinical course. The first case presented with significant mass effect with cerebral herniation and had significant neurological morbidity post-surgery. The second case had minimal symptoms and was managed conservatively with offer of elective surgery. The report underscores the importance of prompt diagnosis and appropriate surgical intervention in managing arachnoid cysts with hemorrhage, highlighting the potential for diverse clinical presentations and outcomes., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: To compare treatment response from the middle cranial fossa repair of superior canal dehiscence (SCD) between cases with and cases without low-lying tegmen (LLT)., Study Design: Cohort study., Setting: Single tertiary care institution., Methods: Two investigators independently reviewed preoperative high-resolution temporal bone computed tomography images and classified the ipsilateral tegmen as either "low-lying" or "control." Patients completed a symptom questionnaire and underwent audiometric testing pre- and post-operatively. Multivariable regression models assessed for symptomatic resolution and audiometric improvement following surgery with tegmen status as the primary predictor. Models controlled for patient age, sex, bilateral SCD disease, dehiscence location, prior ear surgery status, surgery duration, and follow-up duration., Results: Among a total of 410 cases included, we identified 121 (29.5%) LLT cases. Accounting for all control measures, patients with LLT were significantly less likely to experience overall symptom improvement (adjusted odds ratio: 0.32, 95% confidence interval [CI]: 0.18-0.57, p < .001) and reported a significantly lower proportion of preoperative symptoms that resolved following surgery (adjusted β: -25.6%, 95% CI: -37.0% to -14.3%, p < .001). However, audiometric outcomes following surgery did not differ significantly between patients with and patients without LLT., Conclusion: This is the first investigation on the relationship between LLT and surgical outcomes following the middle fossa repair of SCD. Patients with LLT reported less favorable symptomatic response but exhibited a similar degree of audiometric improvement., (© 2023 American Academy of Otolaryngology-Head and Neck Surgery Foundation.)

Background and Objectives: Virtual reality (VR) surgical rehearsal is an educational tool that exists in a safe environment. Validation is necessary to establish the educational value of this platform. The middle cranial fossa (MCF) is ideal for simulation because trainees have limited exposure to this approach and it has considerable complication risk. Our objectives were to assess the face, content, and construct validities of an MCF VR simulation, as well as the change in performance across serial simulations., Methods: Using high-resolution volumetric data sets of human cadavers, the authors generated a high-fidelity visual and haptic rendering of the MCF approach using CardinalSim software. Trainees from Neurosurgery and Otolaryngology-Head and Neck Surgery at two Canadian academic centers performed MCF dissections on this VR platform. Randomization was used to assess the effect of enhanced VR interaction. Likert scales were used to assess the face and content validities. Performance metrics and pre- and postsimulation test scores were evaluated. Construct validity was evaluated by examining the effect of the training level on simulation performance., Results: Twenty trainees were enrolled. Face and content validities were achieved in all domains. Construct validity, however, was not demonstrated. Postsimulation test scores were significantly higher than presimulation test scores ( P < .001 ). Trainees demonstrated statistically significant improvement in the time to complete dissections ( P < .001 ), internal auditory canal skeletonization ( P < .001 ), completeness of the anterior petrosectomy ( P < .001 ), and reduced number of injuries to critical structures ( P = .001 )., Conclusion: This MCF VR simulation created using CardinalSim demonstrated face and content validities. Construct validity was not established because no trainee included in the study had previous MCF approach experience, which further emphasizes the importance of simulation. When used as a formative educational adjunct in both Neurosurgery and Otolaryngology-Head and Neck Surgery, this simulation has the potential to enhance understanding of the complex anatomic relationships of critical neurovascular structures., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Background: The arcuate eminence (AE) is an anatomically consistent bony protrusion located on the upper surface of the petrous bone that has been previously studied as a reference for lateral skull base approaches. There is a paucity of information in the neurosurgical literature seeking to improve the safety of the extended middle cranial fossa (MCF) approach using detailed morphometric analysis of the AE., Objective: To evaluate the use of the AE as an anatomical landmark to help with early identification of the internal acoustic canal (IAC) in MCF approaches by means of a cadaveric study, using a new morphometric reference termed the "M-point.", Methods: A total of 40 dry temporal bones and 2 formalin-preserved, latex-injected cadaveric heads were used. The M-point was established as a new anatomic reference by identifying the intersection of a line perpendicular to the alignment of the petrous ridge (PR), originating from the midpoint of the AE, with the PR itself. Subsequent anatomical measurements were performed to measure the distance between M-point and IAC. Additional distances, including PR length and the anteroposterior and lateral AE surfaces, were also measured., Results: The mean distance between the M-point and the center of the IAC was 14.9 mm (SD ± 2.09), offering a safe drilling area during an MCF approach., Conclusions: This study provides novel information on identification of a new anatomic reference point known as the M-point that that can be used to improve early surgical identification of the IAC., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Here we demonstrate via operative video the subtemporal extradural approach to a tumour in the cavernous sinus., Methods: The extradural approach is performed here in a paediatric patient (a 15-year-old child) via a right extended pterional osteoplastic craniotomy with removal of the zygomatic arch. The operative microscope is introduced, and the dura is divided at the superior orbital fissure into endosteal and meningeal layers using a diamond knife. The middle cranial fossa floor is drilled flat to increase access, and the plane is further developed towards the cavernous sinus. The tumour is seen bulging from within the cavernous sinus, and the cavernous sinus is opened in the anteromedial triangle between cranial nerves Vi and Vii. After biopsy, the tumour is debulked with an ultrasonic aspirator. Doppler is used to identify the internal carotid artery and preserve it. The bone flap is replaced, and the wound is closed in layers in standard fashion., Results: The patient recovered well and was discharged on post-operative day 3. Persistent sixth nerve palsy (present pre-operatively) was present; however, otherwise, there was good recovery from surgery. Good resection of tumour is demonstrated on post-operative MR imaging., Conclusions: This approach is uncommon but important as it enables extradural access to the cavernous sinus, minimising the complications associated with an intradural approach such as cortical injury. In this video, we also demonstrate the fundamental anatomy using annotation and cadaveric images to enhance understanding required for the neurosurgeon to successfully complete this approach. The patient consented to the procedure in the standard fashion., (© 2023. Crown.)

Background: Transorbital endoscopic approaches are becoming increasingly popular for skull base pathologies; the superior lateral orbital portal is one such approach to the middle cranial fossa. This paper provides a technical description that maximises the surgical portal and minimises morbidity., Technical Description: A superior lid crease incision is made extending laterally and the orbital rim is exposed. A subperiosteal dissection of the lateral and superior orbit is performed, with elevation of periosteum off Whitnall's tubercle, ligation of the recurrent branch of the middle meningeal artery, and identification of the superior orbital fissure. The lacrimal keyhole is then drilled away. The middle cranial fossa is accessed by drilling posterior to the orbital rim to expose: the temporalis muscle anterior-laterally, the dura of the temporal lobe posterior-laterally, the anterior cranial fossa superiorly and the periorbita medially., Conclusion: These surgical steps can maximise the surgical portal and minimise morbidity, with avoidance of injury to surrounding structures.

Objectives: To evaluate and compare the long-term results of patients who underwent facial nerve decompression surgery with either transmastoid-supralabyrinthine (TMSL) or combined transmastoid- middle cranial fossa (MCF) approach for traumatic facial nerve paralysis., Materials and Methods: This is a single-center retrospective case-control study. The medical records of traumatic facial paralysis patients with House Brackmann (HB) Grade 6 who underwent facial nerve decompression surgery at via either TMSL or MCF approach between January 2011 and December 2017 were reviewed. The patients who had otic capsule involvement and total sensorineural hearing loss, therefore underwent translabyrinthine facial nerve decompression, and the patients follow-up period has not yet reached four years were excluded from the study. Postoperative HB score and hearing status were compared., Results: Eleven patients were operated with MCF approach (group 1), while 9 patients with TMSL approach (group 2). Average age of patients was 20.04 + 15.2 (range:4-47) years. Three (15 %) patients were female, while 17 (85 %) was male. Geniculate ganglion (90 %) was the most affected segment of the facial nerve. Facial nerve edema was observed in all cases, while intraneural hematoma were encountered in 4 (20 %) cases. Statistically significant improvement in median HB scores were reached in both groups, and no significant difference was observed in post-operative HB scores between both techniques. No significant difference in median AC 0,5-4 khZ and BC 0,5-3 kHz thresholds was observed between both techniques., Conclusion: Even middle fossa approach is the best surgical technique to explore geniculate ganglion and labyrinthine segment of facial nerve, the functional results of transmastoid supralabrynthine approach, which is not needed craniotomy with low complication rate are as successful as middle fossa approach in selected patients., Competing Interests: Declaration of competing interest There is no conflict of interest among the author. There is no financial supporter of this study., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Neurosurgical indications for the superior eyelid transorbital endoscopic approach (SETOA) are rapidly expanding over the last years. Nevertheless, as any new technique, a detailed knowledge of the anatomy of the surgical target area, the operative corridor, and the specific surgical landmark from this different perspective is required for a safest and successful surgery. Therefore, the aim of this study is to provide, through anatomical dissections, a detailed investigation of the surgical anatomy revealed by SETOA via anterolateral triangle of the middle cranial fossa. We also sought to define the relevant surgical landmarks of this operative corridor., Methods: Eight embalmed and injected adult cadaveric specimens (16 sides) underwent dissection and exposure of the cavernous sinus and middle cranial fossa via superior eyelid endoscopic transorbital approach. The anterolateral triangle was opened and its content exposed. An extended endoscopic endonasal trans-clival approach (EEEA) with exposure of the cavernous sinus content and skeletonization of the paraclival and parasellar segments of the internal carotid artery (ICA) was also performed, and the anterolateral triangle was exposed. Measurements of the surface area of this triangle from both surgical corridors were calculated in three head specimens using coordinates of its borders under image-guide navigation., Results: The drilling of the anterolateral triangle via SETOA unfolds a space that can be divided by the course of the vidian nerve into two windows, a wider "supravidian" and a narrower "infravidian," which reveal different anatomical corridors: a "medial supravidian" and a "lateral supravidian," divided by the lacerum segment of the ICA, leading to the lower clivus, and to the medial aspect of the Meckel's cave and terminal part of the horizontal petrous ICA, respectively. The infravidian corridor leads medially into the sphenoid sinus. The arithmetic means of the accessible surface area of the anterolateral triangle were 45.48 ± 3.31 and 42.32 ± 2.17 mm 2 through transorbital approach and endonasal approach, respectively., Conclusion: SETOA can be considered a minimally invasive route complementary to the extended endoscopic endonasal approach to the anteromedial aspect of the Meckel's cave and the foramen lacerum. The lateral loop of the trigeminal nerve represents a reliable surgical landmark to localize the lacerum segment of the ICA from this corridor. Nevertheless, as any new technique, a learning curve is needed, and the clinical feasibility should be proven., (© 2023. The Author(s).)

Background: Adequate epidural procedures and anatomical knowledge are essential for the technical success of skull base surgery. We evaluated the usefulness of our three-dimensional (3D) model of the anterior and middle cranial fossa as a learning tool in improving knowledge of anatomy and surgical approaches, including skull base drilling and dura matter peeling techniques., Methods: Using a 3D printer, a bone model of the anterior and middle cranial fossa was created based on multi-detector row computed tomography data, incorporating artificial cranial nerves, blood vessels, and dura mater. The artificial dura mater was painted using different colors, with 2 pieces glued together to allow for the simulation of peeling the temporal dura propria from the lateral wall of the cavernous sinus. Two experts in skull base surgery and 1 trainee surgeon operated on this model and 12 expert skull base surgeons watched the operation video to evaluate this model subtlety on a scale of 1 to 5., Results: A total of 15 neurosurgeons, 14 of whom were skull base surgery expert, evaluated, scoring 4 or higher on most of the items. The experience of dural dissection and 3D positioning of important structures, including cranial nerves and blood vessels, was similar to that in actual surgery., Conclusions: This model was designed to facilitate teaching anatomical knowledge and essential epidural procedure-related skills. It was shown to be useful for teaching essential elements of skull-base surgery., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: The anterior transpetrosal approach (ATPA) is an effective method to reach lesions in the petroclival region. This approach involves many steps, including superior petrosal sinus (SPS) ligation and tentorial cutting. It is sometimes unnecessary to perform all procedures in the ATPA for certain lesions, especially those centered in the Meckel's cave. Here, we present a simplified anterior transpetrosal approach (SATPA) without superior petrosal sinus and tentorial incision for lesions centered in the Meckel's cave as a modified ATPA., Methods: This study included 13 patients treated with SATPA. The initial steps of SATPA are similar to ATPA, excluding a middle cranial fossa dural incision, SPS dissection, or tentorial incision. Histological examination was performed to understand the membrane structure of the trigeminal nerve, which runs through the Meckel's cave., Results: Pathology revealed trigeminal schwannoma (n=11), extraventricular central neurocytoma (n=1), and a metastatic tumor (n=1). The average tumor size was 2.4 cm. The total removal rate was 76.9% (10/13). Permanent complications included trigeminal neuropathy in four cases and cerebrospinal fluid leakage in one case. Histological examination revealed the trigeminal nerve traverses the subarachnoid space from the posterior fossa subdural space to the Meckel's cave and is covered with the epineurium in the inner reticular layer., Conclusions: We used SATPA for lesions located in the Meckel's cave identified using histological examination. This approach may be considered for small- to medium-sized lesions centered in the Meckel space., Clinical Trial Registration Number: None., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Objective: To evaluate the audiometric outcomes after the middle cranial fossa approach (MCF) for superior canal dehiscence (SCD) repair., Study Design: Retrospective review., Setting: Tertiary referral center., Patients: SCD cases presented to a single institution between 2012 and 2022., Interventions: The MCF repair of SCD., Main Outcome Measures: Air conduction (AC) threshold (250-8,000 Hz), bone conduction threshold (BC) (250-4,000 Hz), and air bone gap (ABG) (250-4,000 Hz) at each frequency, pure tone average (PTA) (500, 1,000, 2,000, 3,000 Hz)., Results: Among 202 repairs, 57% were bilateral SCD disease and 9% had previous surgery on the affected ear. The approach significantly narrowed ABG at 250, 500, and 1,000 Hz. The narrowing of ABG was achieved by both decreased AC and increased BC at 250 Hz, but mediated primarily by increased BC at 500 Hz and 1,000 Hz. Among cases without previous ear surgery, mean PTA remained in the normal hearing range (mean: preop, 21 dB; postop, 24 dB) and clinically important hearing loss (PTA increased by ≥10 dB) after the approach was noted in 15% of cases. Among cases with previous ear surgery, mean PTA remained in the mild hearing loss range (mean: preop, 33 dB; postop, 35 dB) and clinically important hearing loss after the approach was noted in 5% of cases., Conclusion: This is the largest study to date examining the audiometric outcomes after the middle cranial fossa approach for SCD repair. Findings of this investigation support that the approach is effective and safe with long-term hearing preservation for most., Competing Interests: The authors disclose no conflicts of interest ., (Copyright © 2023, Otology & Neurotology, Inc.)

The middle fossa approach is an excellent technique for removing appropriate vestibular schwannomas in patients with serviceable hearing. Knowledge of the intricate middle fossa anatomy is essential for optimal outcomes. Gross total removal can be achieved with preservation of hearing and facial nerve function, both in the immediate and long-term periods. This article provides an overview of the background and indications for the procedure, a description of the operative protocol, and a summary of the literature on postoperative hearing outcomes., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background:  For endoscopic fenestration of middle cranial fossa arachnoid cysts (MCFACs), the decisions on the location and number of stomas are key issues. However, research on this particular topic has been limited. Thus, this study aimed to compare single- versus multiple-stoma endoscopic fenestration for treating Galassi type III MCFACs., Methods:  This retrospective study included 86 patients with Galassi type III MCFACs treated with endoscopic fenestration. Single-stoma fenestration to the basal cistern was performed in 37 cases, whereas multiple-stoma fenestration to the basal cistern and the carotid cistern was performed in 49 cases. Clinicoradiologic profiles and follow-up data were analyzed., Results:  The rate of symptom relief was 83.7% (72/86), and the rate of cyst shrinkage was 96.5% (83/86). Postoperative ipsilateral subdural effusion, which was significant ( p  = 0.042), and noninfectious fever were the two most common complications in the single- and multiple-stoma groups. No significant differences in intraoperative nerve injury, vascular injury, proportion of cases with cyst reduction, and symptom remission rate were observed between the two groups. The rates of cyst recurrence and secondary surgery in the single-stoma group were higher than those in the multiple-stoma group, although the difference was not significant., Conclusion:  Endoscopic fenestration is an effective and minimally invasive approach for treating Galassi type III MCFACs. Single- and multiple-stoma endoscopic fenestrations have the same curative effect., Competing Interests: None declared., (Thieme. All rights reserved.)

Background: The lateral orbitotomy approach (LOA) provides minimally invasive access to the orbit, cavernous sinus region, and middle cranial fossa. Orbital retraction with this approach can nonetheless injure orbital structures, causing unnecessary morbidity., Objective: To describe our clinical experience with the modified LOA (mLOA), wherein the medial aspect of the lateral orbital wall posterior to the orbital rim is preserved., Methods: This is a retrospective, single-institution case series of patients undergoing a mLOA for lesions of the orbital apex, superior orbital fissure, cavernous sinus, and middle cranial fossa. The dimensions and variance of selected anatomic parameters relevant to this approach (orbital rim-superior orbital fossa depth, lateral orbital wall angle) were also analyzed using computed tomography scans from 30 adult patients., Results: Eight patients underwent a mLOA (mean age 54.0 ± 19.6 years; 3 males). Surgical targets included the superior orbital fissure (2; cavernoma and meningioma), sphenoid wing with or without the orbital apex (2; meningioma), cavernous sinus (2; rule out carcinoma and smooth muscle tumor), and anterior/mesial temporal lobe (2; cavernoma). Visual acuity/fields and diplopia was stable or improved in all patients postoperatively. One patient experienced a cerebrospinal fluid leak. On computed tomography analysis, the relevant bony anatomy displayed limited variability, with a mean orbital fossa depth of 42.7 ± 2.8 mm and a lateral orbital wall angle of 44.4° ± 2.7°., Conclusion: The mLOA can provide safe, minimally invasive access to select lesions of the orbital apex, superior orbital fissure, cavernous sinus, and middle cranial fossa. The operative corridor has relatively consistent bony anatomy., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Objective: To determine the safety and effectiveness of the middle cranial fossa (MCF) approach for spontaneous cerebrospinal fluid leak (sCSF-L) repair in class III obese patients. To also assess the need for prophylactic lumbar drain (LD) placement in this patient population., Study Design: Retrospective cohort study., Setting: Tertiary Academic Center., Patients: All patients older than 18 years undergoing sCSF-L repair with an MCF approach., Intervention: An MCF craniotomy for sCSF-L repair., Main Outcome Measure: Rate of complications and postoperative leaks., Results: There were no perioperative complications in 78.9% (56/71) of cases. The surgical complication rate was 12.5% (2/16), 10% (2/20), and 22.2% (6/27) in class I, class II, and class III obese patients. There was no statistically significant difference in complications among these three groups. The most common postoperative complication was a persistent CSF leak in the acute postoperative period with an overall rate of 9.9% (7/71) with six of the seven patients requiring postoperative LD placement. The percentage of postoperative CSF leaks in nonobese, class I, class II, and class III patients were 25% (2/8), 12.5% (2/16), 0% (0/20), and 11.1% (3/27), respectively. There was no statistically significant difference in the rate of postoperative CSF leaks among the four groups (chi-square, p = 0.48). In all cases, the acute postoperative CSF leaks resolved in the long term and did not require further surgical repair., Conclusions: We determine that MCF craniotomy repair for sCSF-Ls is safe in patients with class III obesity, and the incidence of postoperative CSF leaks did not vary among other obesity classes. We also find that prophylactic placement of LDs is not routinely needed in this population., Competing Interests: The authors disclose no conflicts of interest., (Copyright © 2023, Otology & Neurotology, Inc.)

Purpose: Dural exposure during cholesteatoma surgery can pose a risk of cerebrospinal fluid leakage or residual disease. Therefore, delicate handling of the area surrounding the bone defect in the cranial fossa is required. However, in small-sized defects, preoperative prediction of dural exposure can be challenging. This study aimed to evaluate the diagnostic value of computed tomography (CT) for preoperative prediction of cholesteatoma-related dural exposure in bone discontinuities in the skull base., Methods: We evaluated serial high-resolution CT images showing bone density discontinuities in the middle cranial fossa (MCF) requiring mastoidectomy for cholesteatoma. The CT and intraoperative findings were analyzed retrospectively. We evaluated the length between the superior margins of the bone density discontinuities using coronal CT planes. Receiver operating characteristic (ROC) curves were constructed to determine the optimal cut-off values., Results: We extracted data from 107 bone density discontinuities, among which 54 (50.5%) showed dural exposure intraoperatively. Discontinuities with dural exposure (n = 54) had significantly greater lengths than did those without (n = 53) (p < 0.001, Wilcoxon rank-sum test). The area under the curve was 0.9780 according to the ROC analysis, and the optimal cut-off value was determined to be 2.99 mm (sensitivity 92.59%; specificity 94.34%)., Conclusion: A bone density discontinuity length of > 2.99 mm in the MCF on coronal CT plane is a reliable diagnostic marker for cholesteatoma-related dural exposure. Thus, preoperative high-resolution CT analysis can inform optimal surgical preparation and planning before manipulating the area surrounding the osteolytic lesion in the MCF., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Transorbital endoscopic approaches (TOEAs) have emerged as adjunct and alternatives for accessing the middle cranial fossa (MCF). Nuances of the skull base anatomy from a ventral transorbital endoscopic viewpoint remain to be fully described., Objective: To assess the anatomy of the "crista ovale" (COv), described transcranially as the midsubtemporal ridge (MSR), from a ventral transorbital perspective and evaluate its role as a landmark in TOEA to the MCF., Methods: Lateral TOEAs to the MCF were performed in 20 adult cadaveric heads (40 sides). The presence of the COv/MSR was evaluated under endoscopic visualization. Anatomic relationships between COv/MSR and surrounding structures were assessed. The presence of COv/MSR was also examined in 30 cadaveric head computed tomography (CT) scans (60 sides)., Results: The COv/MSR was identified in 98% (39/40) of sides at the MCF, as 1 of 4 major configurations. The COv/MSR was found anterolateral to the foramen ovale and foramen spinosum (mean distance: 9.2 ± SD 2.4 mm and 12.3 ± SD 2.6 mm, respectively) directly anterior or anteromedial to the petrous apex (mean distance: 26.2 ± SD 2.6 mm) and at a mean 47.6 ± SD 4.7 mm from the approach's surgical portal. It was recognized in 95% (57/60) of CT scans., Conclusion: The COv/MSR can be readily identified during TOEA to the MCF and on CT. It serves as a reliable landmark to localize the foramen ovale, foramen spinosum, and petrous apex. Further studies may confirm its surgical significance in transorbital endoscopic procedures., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)